Electronic tube



April 6, 1943. w. w. ElTEL ETAL,

ELECTRONIC TUBE Filed June 50, 194?.

2 Sheets-Sheet 1 ,Z'ZYE'XP ake A. M

E/TEL E EQLLEZUGH THEIR ATTORNEY April 6, 1943. w. w. E|TEL- ET ALELECTRONIC TUBE 2 Sheets- Sheet 2 Y Filed June 30, 1942 WI'ZZSWS ElmBYJAC A. EULZOUCil-l THEIR ATTORNEY Patented Apr. 6, 1943 UNITEDELECTRONIC TUBE William W.

Cullough, Millbrae,

ration of California Eitel, San Bruno, and Jack A. Mc-

Calif., assignors to Eitel- McCullough, Inc., San. Bruno, Calif, acorpo- Application June 30, 1942, Serial No. 449,148

6 Claims.

Our invention relates to an electronic tube particularly adapted fortransmission purposes.

Itis among the objects of our invention to provide an improved structureof, arrangement for and mounting of the electrodes and leads in theenvelope.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of our invention. It is to be understood that we do notlimit ourselves to this disclosure of species of our invention, as wemay adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a perspective view of a tube embodying the improvements ofour invention; and

Figure 2 is a vertical sectional view of the same.

In terms of broad inclusion, our tube comprises an envelope having are-entrant stem at one end. A plurality of coaxial electrodes includ inga plate and grid and cathode are arranged in the envelope, the platebeing provided with a cap at one end thereof. The plate is supported bya bracket on the cap secured to a lead disposed coaxially with theelectrodes and sealed to the envelope end opposite the stem. Leads forthe grid and cathode are sealed to the stem.

In greater detail, and referring to the drawings, our tube comprises anenvelope of glass or the like having a cylindrical body I terminating atthe top in a dome 2 and at the bottom in a reduced neck 3 carrying are-entrant stem 4 having an exhaust tubulation 5. The envelope is fittedwith a cup-shaped base 6, say of porcelain, secured to neck 3 by asuitable cement 'l. Prongs 8 of the usual type project from the base.

Within the envelope are arranged a pluralit. of electrodes including acathode 9, grid H and plate or anode l2. The plate is cylindrical inshape, and may be of any suitable metal, such as tantalum. It preferablycomprises a pair of half-cylinder sections with flanges welded togetherto form heat radiating fins l3. Annular beads H in the sections holdtheir shape when formed in a die. After welding, the fins arecorrugated.

A hemispherical cap I6 of tantalum is secured over the upper end of thetubular plate by depending tabs Il' welded to the rim. Arched recessesl8 formed in the cap between tabs ll provide vent openings. This capprotects the glass dome against electron bombardment, and also adds tothe heat radiating surface of the plate structure.

Plate lead It, preferably of tungsten, is arranged coaxially with theelectrodes and projects through dome 2 at seal 26. The plate issupported by a bracket 2| welded at the lower end to cap 16 and at theupper end to lead [9. This bracket preferably comprises a pair oftantalum straps shaped with curved feet at the bottom to fit the cap forconvenience in welding. The upstanding ends of the straps are grooved toembrace the lead, with laterally projecting portions providing heatradiating fins 22 extending along the lead.

One of the problems in tubes is to prevent heat from flowing out to theglass and cracking the seal. Our structure overcomes this difficulty byreason of the mounting structure above described. As already mentioned,end cap [6 stops electron bombardment of the glass, and helps todissipate heat by radiation before it reaches lead I9. Fins 22 on thebracket also function to dissipate heat tending to flow out along thelead. Angularly disposed slits 23 in fins 22 serve to retard outwardflow of heat by conduction. These features, together with the fact thattantalum is not a good heat conductor, cooperate to thermally isolatethe plate lead and its seal from the heat zone at the electrodes.

Another feature of the plate mounting structure is that a nickel sleeve24 is interposed between tungsten lead I!) and the tantalum bracket.Nickel alloys or fluxes readily with both tungsten and tantalum,insuring a good welded joint between the parts. Furthermore, the weld isclean and free of oxides and contamination which, if present, makeoutgassing diflicult during evacuation.

Grid I I is of the cage type, preferably of platinum wire, terminatingin a tantalum base ring 26. This electrode is supported by brackets 21on a pair of tungsten rods 28 sealed in a press 29 on stem 4. Eachbracket comprises a hairpinshaped tantalum wire welded at the ends togrid ring 25 and at the bight to a rod 28. One of the supporting rods 28serves as a lead and is connected by a flexible extension lead 3| to abase prong 8.

Filamentary cathode 9 comprises a coil of thoriated tungsten welded attop and bottom to a pair of tungsten leads 32 sealed to the stem. Thecathode leads are disposed intermediate the grid leads, all lying in acommon plane passing through the axis of the electrodes. Flexibleextensions 33 connect the lower ends of leads 32 with a pair of baseprongs 8.

A rectifier tube may be made in accordance With the above structure byomitting the grid, in which case the cathode only is supported from thestem.

We claim:

1. An electronic tube comprising an envelope having a re-entrant stem atone end thereof, a plurality of electrodes including a plate and grid inthe envelope, a lead sealed to the other end of the envelope, a cap onone end of the plate, means on the cap for supporting the plate on saidlead, a lead sealed to the stem, and means supporting the grid on thelast mentioned lead.

2. An electronic tube comprising an envelope having a re-entrant stem atone end thereof, a plurality of coaxial electrodes including a plate andgrid in the envelope, a lead coaxial with the electrodes and sealed tothe other end of the envelope, a cap on one end of the plate, means onthe cap for supporting the plate on said lead, a lead sealed to thestem, and means supporting the grid on the last mentioned lead.

3. An electronic tube comprising an envelope having a re-entrant stem atone end thereof, a plurality of electrodes including a plate and gridand cathode in the envelope, a lead sealed to the other end of theenvelope, a cap on one end of the plate, means on the cap for supportingthe plate on said lead, a lead sealed to the stem, means supporting thegrid on the last mentioned lead, and leads for the cathode sealed tosaid stem.

4. An electronic tube comprising an envelope having a re-entrant stem atone end thereof, a plurality of electrodes including a plate and cathodein the envelope, a lead sealed to the other end of the envelope, a capon one end of the plate, means on the cap for supporting the plate onsaid lead, and leads for the cathode sealed to the stem.

5. An electronic tube comprising an envelope, an electrode in theenvelope, a tungsten lead sealed to the envelope, a tantalum bracketsecured at one end to the electrode and welded at the other end to thelead, and a nickel sleeve interposed between the bracket and lead at theweld.

6. An electronic tube comprising an envelope. a grid in the envelopeterminating in a ring, a lead projecting into the envelope, and asupport for the grid comprising a hairpin-shaped wire having its endssecured to said ring and the bight secured to said lead.

WILLIAM W. EITEL. JACK A. MCCULLOUGH.

